A new biodigester that is being loaded with millions of gallons of manure is designed differently from one that leaked 300,000 gallons of animal waste near Waunakee last month.
Dane County officials say they feel confident in safeguards at the new 3-million-gallon digester in the town of Springfield that is scheduled to start generating electricity this month.
Meanwhile, state and local regulators said that now that the cleanup near Waunakee is complete, they expect to learn how the older Clear Horizons digester plans to minimize damage from any future messes like the one that went undetected for hours and ended up tainting Six Mile Creek.
“They said they were looking into and exploring the capabilities of their system,” said Josh Wescott, chief of staff to County Executive Joe Parisi. “We’re going to want to make sure there is adequate alarm capacity.”
Wescott said the county also wants assurances that the Clear Horizon facility is adequately staffed.
The spill occurred when a pipe outside the digester’s containment berm ruptured for undisclosed reasons when no employees were present, no alarm system was triggered and no automatic shutoff valve stopped the flow.
It was the second spill in the Lake Mendota watershed this year. After a spill of similar size at UW-Madison’s Arlington Agricultural Research Station in February, UW officials added a containment berm and a $3,000 automated shutoff valve after the failure of a pipe fitting resulted in pollution of the Yahara River.
State and federal officials said they would begin reexamining regulations around manure storage because of the spills. Data released by the state showed only one larger leak has been reported in the past 15 years.
The new biodigester was built in the town of Springfield by the LaCrosse-based Gundersen Health System and US Biogas.
“We have a high level of confidence with the Biogas digester,” Wescott said.
The county assisted in planning and finding financing for both digesters.
They are designed to generate electricity and reduce the nutrient level and volume of cow manure, which eventually goes back to nearby farms to be spread on fields as fertilizer. Runoff of farm nutrients are the major source of smelly overgrowths of weeds and algae in lakes.
The Gundersen-Biogas facility is equipped with a 15-million-gallon storage structure that can receive manure in case of a spill, said Kevin Connors, director of the county Land and Water Resources Department.
It took about two weeks for crews to clean up the Waunakee spill. Several farmers agreed to spread manure on fields or deposit it in storage lagoons, Connors said.
The Gundersen-Biogas storage structure is built partly below ground and partly above ground, Connors said.
Connors said there are other safety precautions, but he deferred to Gundersen officials to describe them.
A company spokesman didn’t respond to phone and email messages.
A strong safety design is needed because a section of the North Fork of Pheasant Branch creek flows within a few hundred feet of the site, Connors said.
Meanwhile, County Board members said the Waunakee spill has prompted them to take a second look at the design of a proposed private digester in the town of Bristol before they grant it final approval.
About 25 people attended a meeting Monday night of the County Board’s Agriculture, Environment and Natural Resources Committee in Waunakee to ask questions about the Clear Horizons spill.
Nila Frye, who operates a child care center in the village, said the public should have been notified more quickly about the spill. If it had been summer, children could have been exposed to the manure while playing in the creek, Frye said.
Clear Horizons sent out a press release about the spill several days after it occurred.
Company operations manager Monte Lamer said he should have notified the chairman of the town of Vienna, where the facility is located, but he “dropped the ball.”
The first priority was the cleanup effort, Lamer said.
DNR regional director Mark Aquino said the state would have made an announcement if the spill posed a potential health risk.
Six Mile Creek had an odor and it was discolored near where the spill reached it, but no fish kills have been reported, DNR officials said.
Preliminary monitoring of the creek has found elevated phosphorus levels, but the levels aren’t nearly as high as they are during heavy rain or snow melts, Wescott said.
See also Dane County Executive, Joe Parisi’s editorial “Digesters key to cleaning our lakes”